Schaeffer Manufacturing Co. 0700CK4-012 SynShield Durability Advantage 15W-40 Diesel Engine Oil, 12-Quart Bottle (Pack of 12)

After 2 hours run time its still clean.

Best oil on the market it’s the only oil I’ve used in my medium and heavy duty trucks.

Travel between Texas and Wisconsin several times a year. This oil has out performed all others hands down. My 2013 F-350 is a happy machine. Mileage Increased also by a mile per gallon.

I’ve put 110k miles on my truck over the last three yrs and finally switched to Schaefer’s. She’s instantly running more smoothly than I remember before the wear and tear. Impressive stuff. Should’ve started using it BEFORE all those miles but this has definitely made a notable improvement.

This is a good product, this price was better than what Schaeffer direct offered. To get better, my order would have to be a lot bigger. The convenience of delivery was helpful. At one time there was much less costly Chinese alternative but no longer available and it didnt have the ratings CK that this purchase offered.

Great fuel economy, incredible oil!

I bought this oil for my 2019 GMC Sierra Duramax diesel, however my owners manual clearly states API CJ-4, ONLY!!! However, further on in my owners manual it includes CK-4??? It would stand to reason that API CK-4 rated oil would be superior to API CJ-4 as this rated oil is older and does not include the latest additives. GM needs to do a better job proofreading their manuals before issuing them with new trucks.

Top of the line oil for the Powerstroke.

Case leaking oil when it arrived

Good oil.Had it before, but dropped after ingine start eating oil.Since bouthg different semi start using again.